Observation of Color Change in Carpet Samples Prepared by the JIS Soiling Tester during the Soiling Process

Abstract

The observed color change in carpet samples prepared by a laboratory soiling tester during the soiling process was analyzed by L^*, a^* and b^* in the CIELAB system. Ten commercial tufted carpets were used as samples. Laboratory soiling tests were performed using a rotary tapping soiling tester according to the Japanese Industrial Standard (JIS) accelerated soiling test method. The numbers of cycles for the JIS soiling tester were 25, 50 and 100. The color of the soiled samples was measured after each corresponding number of cycles. L^* of the samples having high L^* values, such as L^*＞60, decreased significantly during the soiling process. A high correlation (r²=0.983) between the lightness difference (ΔL^*) and the color difference (ΔE^*ab) was obtained from the JIS soiling tests. The color of the standard soiling compound used in the soiling test was L^*=31.82, a^*=2.11 and b^*=5.34. L^*, a^* and b^* of all the samples converged to the color of the standard soiling compound as the soiling process progressed. The coefficients of determination (r²) calculated from ΔL^* obtained from a total traffic of 6000 people in the practical use test and JIS soiling tests were from 0.802 to 0.817. The r² values of ΔE^*ab were from 0.895 to 0.921.